Mid-Atlantic Fishing

VHF Marine Radios

VHF marine radios are essential equipment for most fishing boats.
The usable range of a VHF radio system is dependant on several factors including
the weather, the boat , the antenna, and the health of the radio. The most
important part of the system is the antenna. Marine antennas should be mounted
as high as practical. Another important quality of an antenna is it's gain.

Gain is rated in decibels or dB. Most experts recommend
a quality antenna with 6 a gain of dB for powerboats under 50 ft. The antenna
system can be tested by measuring the VSWR of the antenna. The VSWR should
be as low as possible, typically 1.5 to 1 or lower on a healthy antenna.

Other radio problems can stem from the radio or the
vessel electrical system. One of the most frequent radio system failures on a
powerboat is when a poor connection, normally from corrosion, exists between the radio and
battery. The radio will normally come on but may transmit erratically or not at
all. If other accessories such as gps units are on the same circuit, keying
the radio transmitter will likely reset or shut down these devices. This is a most
annoying and dangerous problem which is more often than not intermittent. If the
trouble can be duplicated, it can be located easily by checking voltage along
various parts of the radio power circuit while having a helper key the radio.
Battery voltage should be around 12.5 volts and should not drop more than
about .1 volts across any connector, fuse, etc. when the transmitter is keyed.
Some small drop is normal but trouble is likely if the radio is not getting at
least 12 volts all the time.

Marine radios, GPS units, and other devices can suffer from interference on a boat.
Electrical interference usually originates from other sources in the boats electrical system.
One common example is "clicking" or "pinging" heard in the radio when a fish finder is on.
This and other odd symptoms can be minimized by running the proper sized electrical power wiring
for each device all the way to the battery switch. In some cases electrical
filters will need to be installed to combat interference.

Two systems that boaters may want to learn about
are Digital Selective Calling (DSC) and the Global Maritime Distress and Safety
System (GMDSS). DSC is secure digital format which allows users to communicate
with other DSC equipped radios. In a nutshell GMDSS is a system that allows a
radio to send an automated distress call which can include vessel position
information..... IF....... the radio is connected to a working GPS unit.